Thanks. Everything I find on the 1863/1864 show a band type mount that goes all the way around the barrel and stock. Mine has small rings/tubes welded to the barrel that hold the end of the packing rod. Were these added and welded on as a later modification when reducing the stock foregrip length? I assumed they were in the original design looking at it, but this in by no means my area of expertise.
When your musket was manufactured it looked like this:
The musket shown here is a US Model 1864 (sometimes referred to as a Model 1863 type 2). For additional views of this musket and an excellent write-up on the M1864, see the original listing from College Hill Arsenal
here.
The Model 1864 differs from the Model 1863 in a few minor ways as listed below:
1) The upper and rear barrel bands of the M1864 are solid, where as the M1863's are "clamp-on" style with a cut at the bottom.
2) The Model 1864's barrel bands are retained by band springs, where as the M1863's are held fast by adjusting a tightening screw at the bottom of each band.
3) The Model 1864 has a simplified rear sight that eliminated the middle 300 yard sight leaf. Instead, the 500 yard leaf has a hole in it for 300 yard ranges.
4) The ramrod of the M1864 was redesigned and looks more like a P1853 ramrod head, although the example here is equipped with an earlier M1863 style ramrod.
There are a couple of other very minor changes, like the shape of the trigger bow lugs, and some of the small screws being polished bright as opposed to heat blued.
The ramrods of all US rifles and muskets after the production of the Model 1803 rifle ended were secured in a channel drilled into the forearm of the gun's stock. When your musket was shortened and the forearm cut away it deprived the gun of its ramrod channel. In order to keep a ramrod with the gun the "tubes/rings" you mentioned (the common phraseology is ramrod pipes) were soldered to the underside of the barrel.
Hope that clears some things up for you,
Garrett